Labyrinth and Piano Key Weirs

Labyrinth spillways are almost as old as dam engineering. In spite of the fact that they appear as a very good technical-economical compromise, only 0.1% of large dams are equipped with such weirs. The main reason for this is that traditional labyrinth weirs usually cannot be installed on top of concrete gravity dams as they require a large foundation surface. In 2003 an improved concept of traditional labyrinth spillway emerged, with alveoli developed in overhangs from a reduced support area: the Piano Key Weir (PKW). The Piano Key Weir is a weir of particular geometry, associating to a labyrinth shape the use of overhangs to reduce the basis length. The main advantage of Piano Key Weirs is that it can be directly placed on a dam crest. As a result of extreme fl oods in the recent past, a growing demand for safety in society, and revised hydrological calculations, the need for reliable spillways has consequently become higher. In this context, the Piano Key Weir proves to be an interesting solution to increase the hydraulic capacity of spillway devices.
The book contains the state-of-the-art on this still non-conventional hydraulic structure, and is divided into six main themes:

Physical Modeling. Hydraulic capacity
Physical Modeling. Downstream fittings
Numerical Modeling
Hydraulic Design
Planned and achieved projects
Nomenclature, Database, Future developments.
The papers in Labyrinth and Piano Key Weirs demonstrate that dam engineering currently experiences a strong revival of labyrinth oriented weirs, and are particularly of interest to academia, researchers and professionals working in the area of hydraulic engineering, and to dam control authorities and dam owners.

Preface
Acknowledgements
Organization
Organizing institutions and sponsors
Keynote lectures
From Labyrinth to Piano KeyWeirs – A historical review, A.J. Schleiss
General comments on Labyrinths and Piano KeyWeirs: The past and present, F. Lempérière, J.-P. Vigny &A. Ouamane
Hydraulic characteristics of labyrinth weirs, B.M. Crookston & B.P. Tullis
Physical modeling – Hydraulic capacity
PKWeir and flap gate spillway for the Gage II Dam, V. Dugué, F. Hachem, J.-L. Boillat, V. Nagel, J.-P. Roca & F. Laugier
Piano KeyWeir design study at Raviege dam, S. Erpicum, V. Nagel & F. Laugier
Nine years of study of the Piano KeyWeir in the university laboratory of Biskra “lessons and reflections”, A. Ouamane
Influence of the Piano KeyWeir height on its discharge capacity, O. Machiels, S. Erpicum, P. Archambeau, B. Dewals & M. Pirotton
Study of optimization of labyrinth weir, M. Ben Saïd &A. Ouamane
Influence of Piano KeyWeir geometry on discharge, R.M. Anderson & B.P. Tullis
Study of piano-key morning glory to increase the spillway capacity of the Bage dam, G.M. Cicero, M. Barcouda, M. Luck & E. Vettori
Physical modeling – Downstream fittings
Contribution to the study of the Piano KeyWeirs submerged by the downstream level, F. Belaabed &A. Ouamane
Flow properties and residual energy downstream of labyrinth weirs, R. Lopes, J. Matos & J.F. Melo
Energy dissipation on a stepped spillway downstream of a Piano KeyWeir – Experimental study, S. Erpicum, O. Machiels, P. Archambeau, B. Dewals, M. Pirotton & C. Daux
Coupled spillway devices and energy dissipation system at St-Marc Dam (France), M. Leite Ribeiro, J.-L. Boillat, A.J. Schleiss & F. Laugier
Energy dissipation downstream of Piano KeyWeirs – Case study of Gloriettes Dam (France), M. Bieri, M. Federspiel, J.-L. Boillat, B. Houdant, L. Faramond & F. Delorme
Numerical modeling
A sensitivity analysis of Piano KeyWeirs geometrical parameters based on 3D numerical modeling, J. Pralong, F. Montarros, B. Blancher & F. Laugier
Hydraulic comparison between Piano KeyWeirs and labyrinth spillways, B. Blancher, F. Montarros & F. Laugier
1D numerical modeling of the flow over a Piano KeyWeir, S. Erpicum, O. Machiels, P. Archambeau, B. Dewals & M. Pirotton
Influence of structural thickness of sidewalls on PKW spillway discharge capacity, F. Laugier, J. Pralong & B. Blancher
Experimental study of side and scale effects on hydraulic performances of a Piano KeyWeir, G.M. Cicero, J.M. Menon, M. Luck &T. Pinchard
Hydraulic design
Study of optimization of the Piano KeyWeir, A. Noui &A. Ouamane
Experimental parametric study for hydraulic design of PKWs, M. Leite Ribeiro, J.-L. Boillat, A.J. Schleiss, O. Le Doucen & F. Laugier
Main results of the P.K weir model tests in Vietnam (2004 to 2010), M. Ho Ta Khanh, T. Chi Hien & N. Thanh Hai
Piano KeyWeir preliminary design method – Application to a new dam project, O. Machiels, S. Erpicum, P. Archambeau, B. Dewals & M. Pirotton
Method to design a PK-Weir with a shape and hydraulic performances, G.M. Cicero
Planned and existing projects
Lessons learnt from design and construction of EDF first Piano KeyWeirs, J. Vermeulen, F. Laugier, L. Faramond & C. Gille
P.K weirs under design and construction in Vietnam (2010), M. Ho Ta Khanh, D. Sy Quat & D. Xuan Thuy
Spillway capacity upgrade at Malarce dam: Design of an additional Piano KeyWeir spillway, T. Pinchard, J.-M. Boutet & G.M. Cicero
Rehabilitation of Sawara Kuddu Hydroelectric Project – Model studies of Piano KeyWeir in India, G. Das Singhal & N. Sharma
A dam equipped with labyrinth spillway in the Sultanate of Oman, L. Bazerque, P. Agresti, C. Guilbaud, S. Al Harty &T. Strobl
Labyrinth fusegate applications on free overflow spillways – Overview of recent projects, M. Le Blanc, U. Spinazzola & H. Kocahan
Nomenclature, data base, future developments
A naming convention for the Piano KeyWeirs geometrical parameters, J. Pralong, J. Vermeulen, B. Blancher, F. Laugier, S. Erpicum, O. Machiels, M. Pirotton, J.-L. Boillat, M. Leite Ribeiro &A.J. Schleiss
Creation of a PKW Database – Discussion, J.-L. Boillat, M. Leite Ribeiro, J. Pralong, S. Erpicum & P. Archambeau
Development of a new concept of Piano KeyWeir spillway to increase low head hydraulic efficiency: Fractal PKW, F. Laugier, J. Pralong, B. Blancher & F. Montarros
General comments on labyrinths and Piano KeyWeirs – The future, F. Lempérière & J.-P. Vigny
Research axes and conclusions, S. Erpicum & J.-L. Boillat
Author index